In the Czechoslovak Inventorship Certificate No. 188,085 there is disclosed a device for exchanging wound bobbins taken off bobbin holders for empty tubes. The device comprises a conveying channel arranged for swinging about a pivot and is provided with a forcing-out wedge for releasing the bobbin, and a positively swingable transferring arm with a cam which is in an active connection with a follower on a balance beam arranged fro swinging on said conveying channel while another follower on said channel is coupled with a cam provided on the device frame. During the bobbin exchange, the conveying channel, after unlocking an arresting pin, will swing downwards by gravity and surround the package on the bobbin in the bobbin holder. By the action of the forcing out wedge, the bobbin is disengaged from clamping discs of the bobbin holders so that it falls, due to its own weight, into the conveying channel. The conveyor channel and the transferring arm are then positively swung upwards together with the full bobbin where, under assistance of the cam and the balance beam mechanism, the bobbin is delivered onto a chute on which it slides by gravity up to a conveyor belt extending along the bobbin holders on the machine frame.
This known device is disadvantageous because the full bobbin, after having slid upon the chute, is not always deposited into the conveyor belt in the correct position whereby, when being transferred at the belt end to another device such as a packeting or another automatic mechanism for bobbin manipulation and delivery, some troubles may occur. Such a drawback is not even avoidable by providing the conveyor belt with channel-forming guide walls. Especially disadvantageous is the use of this device for conical bobbins which may get jammed and assume, with their minor diameter end, a different position every time. During such malpositioning, the package may be damaged.
Another known device according to the U.S. Pat. No. 4,355,859 comprises, on the travelling service unit, arms for forcing the full bobbin out of the bobbin holders, and has similar disadvantages are referred to hereinabove. After the full bobbin has been disengaged from the bobbin holders, it is transferred to a sheet metal chute on which it slides downwards by its own weight onto a conveyor belt. Since the chute slope is oriented perpendicularly to the direction of a running conveyor belt, it is just the transition between the chute and the running belt that causes the full bobbin to assume an incorrect position on the belt.
According to the U.S. Pat. No. 4,171,779 there is also known a device for exchanging full bobbins for empty tubes, said device being also adapted for travelling along the bobbin holders on the textile machine. The device is provided with gripping means designed for somewhat lifting the full bobbin, after releasing the bobbin holders, whereupon the bobbin is transferred to conveying means by which it is carried up to the end of the machine. Here the bobbin is disengaged from said conveying means and slides on a chute, by gravity, onto a conveyor belt. Thus, the displacement of the full bobbin from the chute onto the conveyor belt is, in this case, also uncontrollable which gives rise to the same drawbacks as with the devices previously referred to.